Researchers publishing in Age and Ageing have found that, rather than being protective, an increase in dietary protein is associated with an increased chance of sarcopenia.
Sarcopenia is a well-known disorder that occurs with aging. People with sarcopenia lack adequate muscular function, leading to frailty, a higher risk of falls, and a functional decline in daily living activities that leads to a decreased quality of life [1].
Previous research into the relationship between protein consumption and sarcopenia has noted the phenomenon of anabolic resistance, in which muscle protein is more difficult to synthesize in older adults [2]. Therefore, the European Society for Clinical Nutrition and Metabolism (ESPEN) recommends that older adults consume 1 to 1.3 grams of protein per kilogram of body weight a day [3].
Muscle strength, muscle mass, and sarcopenia
This study used data from the TwinsUK cohort, a registry of almost 15,000 fraternal and identical twins and triplets [4]. This study chose community-dwelling older adults that had detailed muscular data available; this was a subgroup of 3,302. There were no exclusionary factors.
As is usual for this kind of study, there were a substantial number of confounding factors, many of which were related to one another. While aging is, of course, the primary association, education, BMI, and income were all found to have associations with muscle strength, muscle mass, and sarcopenia.
There was no significant association between muscle strength and protein intake one way or another. However, protein intake below the ESPEN recommendations was, to the researchers’ surprise, significantly correlated with a reduced incidence of low muscle mass and sarcopenia. Similarly, protein intake in excess of the ESPEN recommendations was correlated with a greater risk of low muscle mass and sarcopenia.
These results were confirmed when twins were examined against one another. Shared twin factors, such as genetics and early life history, did not meaningfully change the statistical relationship between protein intake and sarcopenia. Other multivariable analysis models also confirmed these findings.
Analysis
The researchers considered multiple potential reasons behind these findings. One of them is the idea that the causality might be reversed: that people who suffer from sarcopenia may be consuming more protein in an effort to treat the condition. The researchers find this to be unlikely, as sarcopenia is seldom diagnosed [5].
They also note that dietary studies that did not focus on protein, but rather on higher consumption of fruits and vegetables, showed an association with higher grip strength [6]. Diets that are high in protein might also be high in inflammatory or other negative factors that promote sarcopenia, so it might be the source of protein that is the root cause of these results.
Conclusion
While this study was biased towards healthy volunteers, it offers highly contrary evidence to the conventional wisdom surrounding protein and sarcopenia, and it may result in re-evaluations of ESPEN and other dietary health guidelines. This is an association study that does not prove causation, but it makes it clear that simply eating more protein is not likely to protect anyone against developing sarcopenia. Exercise may be somewhat effective in fighting back against this disease, but more fundamental biological interventions are likely to be required to prevent it for good.
Literature
[1] Cruz-Jentoft, A. J., Bahat, G., Bauer, J., Boirie, Y., Bruyère, O., Cederholm, T., … & Zamboni, M. (2019). Sarcopenia: revised European consensus on definition and diagnosis. Age and ageing, 48(1), 16-31.
[2] Welch, A. A. (2014). Nutritional influences on age-related skeletal muscle loss. Proceedings of the Nutrition Society, 73(1), 16-33.
[3] Deutz, N. E., Bauer, J. M., Barazzoni, R., Biolo, G., Boirie, Y., Bosy-Westphal, A., … & Calder, P. C. (2014). Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group. Clinical nutrition, 33(6), 929-936.
[4] Verdi, S., Abbasian, G., Bowyer, R. C., Lachance, G., Yarand, D., Christofidou, P., … & Steves, C. J. (2019). TwinsUK: the UK adult twin registry update. Twin Research and Human Genetics, 22(6), 523-529.
[5] Avgerinou, C. (2020). Sarcopenia: why it matters in general practice. British Journal of General Practice, 70(693), 200-201.
[6] Robinson, S. M., Jameson, K. A., Batelaan, S. F., Martin, H. J., Syddall, H. E., Dennison, E. M., … & Hertfordshire Cohort Study Group. (2008). Diet and its relationship with grip strength in community‐dwelling older men and women: the Hertfordshire cohort study. Journal of the American Geriatrics Society, 56(1), 84-90.
14 Comments
Pierre Gaudette
February 24, 2023
What kind of protein ? Read meat, bacon or plant based ?
Kraig Thompson
February 24, 2023
I’d venture to say anything that might harm a precious animal. Early humans actually ate alongside their ruminant partners. Only problem is we don’t have the 4 tummies for it.
Jeroen Harms
March 5, 2023
Funny because I would say the exact opposite. Animal protein has more sulfur content and more nitrogen compared to plant based protein that only has 1/3rd of these compounds. Why does that matter? Well in order to stabilize blood PH we need to free up calcium to reduce the acidity effects of sulfur and nitrogen. People forget Calcium is an essential building block to muscle mass and when released it can lead to reduction in muscle mass. If demand it too high it gets freed up from the muscles as well.
So that leads to the problem of having 3times more of these compounds in your diet from protein leading to an 3 fold increase in released calcium. Which is a compound that at older age is not absorbed well and known to be problematic by reduced levels of it in bones but also in muscle.
So from a mechanical biological point of view. The plant based protein would put a loss less burden on these systems making you sustain bone mineral density and muscle mass much longer. This is one of the reasons plant based diets are so well correlated with longevity and healthspan in Blue Zones.
So this “4 tummy” reasoning. Really no evidence based here.
Phil Goetz
March 11, 2023
Good point–and I’d like another category, milk-based. The protein in milk is quite different from both meat and plant protein, and more-problematic wrt inflammation IIRC.
David Ingalls
February 24, 2023
Was this controlled by protien type (eg; animal versus plant)? If not the conclusion is useless.
Jeroen Harms
March 5, 2023
Why would it be useless? At this level of ingestion the ratio of amino acids has no influence on the effect of the protein where saturation of minimum requirements is already med. The 1:1 amino acid composition ratio is only relevant in a sub par environment where people are struggling to get the minimal RDA. Only in that case animal protein would be preferred just to make sure the minimal levels are med, though soy or pea protein would suffice as well.
People really need to get in their head that beyond that 50 grams protein per day line… there is not significant difference in amino acid profiling that is going to have an impact. Where we only know that BCAA’s and Methionine in too high prominent amounts acan be problematic for longevity. That is something we can actually avoid by filling up the baseline with lower BCAA/Methione soucres. When we hit the 70 gram we are fully saturated to the minimum levels of these AA’s but actually got more of the rest providing non deleterious functions for longevity.
Plant protein mechanistically always comes out on top. I would even state going easy with the soy because of the 1:1 profile.
Phil Goetz
March 11, 2023
We already know that red meat has a much worse effect on the cardiovascular system, and on inflammation, than chicken meat or plant protein, and I’m pretty sure that has nothing to do with AA ratios. The bad effects of milk protein are controversial, but the clear pattern is that different proteins have effects that differ due to factors other than their AA composition.
Smile
February 24, 2023
This could literally also be explained if it turned out higher protein diets typically with lower vegetable and fruit intake.
That would explain everything and not be contrary to current recommendations or understandings.
Nat
February 25, 2023
So there is the right amount and more is not always better?
Kraig Thompson
February 26, 2023
We all know everything in life should be consumed in moderation. My issue with this study is that there’s zero controls.
Me
February 25, 2023
I feel the conclusion of this study is a starting point for future analysis delving in deeper to the exact causations and correlations between all factors. A beginning, not an end. In the beginning of the article it states: “The results were the opposite of expected”. Which I believe to mean: Hey! We started out trying to prove on thing, but ended up proving the opposite! Now we have to figure out what this means! For a person in today’s society, trying to add more protein into a diet usually means easier and more accessable protein. Synthetic, super processed, easy to eat/drink protein. These are not conducive to healthy building blocks and function. In fact, our bodies have to work twice as hard to process them and receive half the benefits. Vegetables have raw, natural…well everything. But even these are GMO’ed, picked green for transport, contain chemicals and lack what once was. Our fresh protein options are the same. Our desire for a quick, more accessible life/world has thus made age deterioration that much quicker and “more accessible”. But I digress, I feel this article is founded around the idea that we’re left with a question, not an answer. Therefore is not useless. It’s an incredible starting point into discovering a correlation against a previously believed answer. At no time did they state that protein types were a study point. In fact they said they weren’t. Just the amounts of protein in concordance with the RDA for this specific disease. You can’t have a preconceived idea of what something is saying (because it’s what you want) going into anything, you will only stunt your ability to learn and grow. This article is fascinating and well written. I appreciate the honesty and the thought process, as well as the desire to challenge our previous ideals for the betterment of ourselves and others! Especially knowing most people are too close minded to appreciate it. I look forward to seeing what new conclusions are formulated concerning this in the future!
Thank you!
Donna Galbreath
February 26, 2023
I need more variables in order to try to understand where I might fit into this phenomenon. Please continue your research. I’m interested in how this would affect diabetics and what demographics were studied. Thank you for giving me something to consider in my healthcare journey.
Brad
March 5, 2023
Dr Brad Stanfield points out what he believes to be flaws in the study and suggests that the preponderance of clinical evidence is in favor of higher protein for older adults. From purely a taste preference, I prefer less protein. I can’t say that I know what’s healthiest.
Here is Dr. Stanfield’s criticism of the study:
https://www.youtube.com/watch?v=jQFDV5L2Nlg
Phil Goetz
March 11, 2023
With a result like this, we really need to see the plot of the datapoints, not just the results of a statistical test comparing points left of ESPEN with points to its right. The main problem is that a plot of vs. always is a U curve, not a straight line. This kind of analysis assumes that the relationship is a straight line, which is almost always wrong.
Write a comment: